Is there a schematic of the Duo available anywhere?
My reason for asking is twofold:
Firstly, I want to know if the GND of the MIDI IN and USB are directly connected. This is because I want to send messages to the MIDI IN from a microcontroller powered by the Duo’s USB port. So if the GND is shared, I don’t have to connect anything to the MIDI IN’s GND.
Secondly, schematics are cool. I just want to look at it. And maybe if I have a similar question in the future I’ll just look at the schematic
Hi @Schwalb!
The Schematics of the MOD Duo are not publicly available.
For MIDI all MOD Devices follow the MIDI specification so there is no ground connected there, as it would break the spec.
For a less cable approach, you could of course also use MIDI over USB if thats an option for you 
Does the MOD use the pre or post 2014 MIDI spec? The post 2014 one supports 3.3V logic also, but the pre 2014 one doesn’t
After looking at the schematic of the new midi spec I see that that doesn’t matter. The midi in port is identical